Security document and security element for a security document

ABSTRACT

Security element  2, 4  to be embedded in or applied to a security document so that it is visually recognizable from both sides of security document  1  is of multilayer construction and includes interference element I with a color shift effect and diffraction structures  8 . Depending on the arrangement of the layers and existing diffraction structures  8  on transparent substrate S the color shift effect and/or the diffractive effects are perceptible from one or both sides of security element  2, 4 . The security element is suitable in particular as two-sided windowed thread  4  and as label or transfer element  2  over hole  3.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase of International Application SerialNo. PCT/EP03/01677, filed Feb. 19, 2003.

FIELD OF THE INVENTION

This invention relates to a security element and to a security document,in particular paper of value such as a bank note, having such a securityelement. The invention likewise relates to a semifinished product forproducing such a security document. In particular, the invention relatesto a security element in the form of a security thread to be embedded inthe security document as a so-called windowed thread and in the form ofa label or transfer element to be applied to the security document.

DESCRIPTION OF THE BACKGROUND ART

Security documents according to the present invention are in particularbank notes but also checks, check cards, credit cards, ID cards,passports, admission tickets, travel tickets and the like. Semifinishedproducts for producing the aforementioned security documents may be forexample unprinted security paper and other unprinted security documentsubstrates.

SUMMARY OF THE INVENTION

The aforementioned security documents are usually equipped with embeddedsecurity threads or applied security labels or transfer elements forprotection against imitation and as proof of authenticity. Securitythreads in the form of windowed threads are widely known for example inconnection with documents of value such as bank notes, but are alsofundamentally suitable for use in check cards and the like. Windowedthreads are embedded in the basic material of the security document andappear periodically on the security document surface so that they arevisually recognizable in these “window areas.” In translucent substratesthere is a so-called reflected/transmitted light effect whereby thesecurity thread appears as a dark strip compared to the surroundingmaterial when viewed in transmitted light. In reflected light, however,the security thread is only recognizable in the window areas.

There is a distinction between simple windowed threads appearing only onone surface, and two-sided windowed threads appearing on both surfaces,a special case of the two-sided windowed thread being referred to in thefollowing as a lookthrough windowed thread, which is visiblesimultaneously from both sides of the document of value. A lookthroughwindowed thread spans a hole or transparent area in the document ofvalue, so to speak. A further two-sided windowed thread is the securitythread referred to hereinafter as an alternating windowed thread, whichis visible alternately on the front and back of a document. Alongsidesecurity threads, it is also possible to use so-called transfer elementsas security elements, these usually spanning gaps, e.g. a hole, in adocument.

The security elements have complex security features that are checkablevisually and/or by machine and are imitable only with great effort. Toadditionally increase the protection from forgery, such securityelements frequently have a plurality of different security features thatcan also have a new joint effect in combination.

A security feature frequently encountered in security elements is amultilayer dichroic coating whose color effect changes depending on theviewing angle and/or depending on viewing in transmitted light orreflected light. This phenomenon is based on interference effects due tothe overlay of multiple reflections and/or transmissions of light waveswithin the layer structure in combination with selective absorptionproperties of the layer materials. The color change at varying viewingangle is also referred to as a color shift effect. The color change uponalternating viewing in reflected light and transmitted light, however,will be designated a color change effect in the following.

Optical interference coatings with a color shift effect are described inconnection with security elements for example in EP 0 341 002 B1 andU.S. Pat. No. 3,858,977. Depending on the type and number of layers inthe layer structure, there may be two, three, four or more differentcolor effects dependent on viewing angle. The reflection andtransmission properties of such color shift effect layers depend on aplurality of factors, in particular the refractive indexes, absorptioncoefficients and layer thicknesses as well as the number of layers ofthe layer structure.

Although security elements with a dichroic coating have been proposed,there is still a need for improved security elements.

The problem of the present invention is therefore to provide securityelements, in particular a security thread or transfer element, that haveelevated forgery-proofness in comparison with the prior art.

This problem is solved according to the invention by a security elementand a security document or semifinished product having the featuresdescribed herein. Advantageous developments and embodiments of theinvention are also described herein.

Accordingly, the security element includes a multilayer interferenceelement that produces a color shift effect on both the front and theback of the security element when the security element is viewed atdifferent angles. The color shift effect can be designed to be identicalor different on the front and back of the security element.

In addition, the security element preferably has diffraction structuresthat at least partly overlap the interference element.

Due to the complex multilayer structure of the security elements and thethus poorly copiable diffractive, color shift and color change effects,they are imitable only with great effort.

The interference element is constituted by superimposed interferencelayers, the absorber and dielectric layers, whereby a plurality ofabsorber and dielectric layers can also be superimposed alternately.Instead of alternating absorber and dielectric layers, solely dielectriclayers can also be provided, whereby adjacent layers have very differentrefraction indexes so that a color shift effect is produced. The use ofabsorber layers is advantageous, however, because the color shifteffects are better visible.

Interference element I can fundamentally be of multilayer structure, butpreferably includes at least three interference layers, namely twoabsorber layers A₁, A₂ and dielectric layer D located between theabsorber layers. Such a three-layer interference element can cause adichroic color shift effect at changing viewing angles and/or at achange between reflected light and transmitted light viewing. Furtherdielectric and/or absorber layers in alternating order can achievefurther color changes or intensify color changes.

Absorber layers A1, A2 typically used are metal layers made of materialslike chromium, iron, gold, aluminum or titanium in a thickness ofpreferably 4 nanometers to 20 nanometers. Absorber layer materials usedcan also be compounds like nickel-chromium-iron or rarer metals likevanadium, palladium or molybdenum. Further suitable materials are e.g.nickel, cobalt, tungsten, niobium, aluminum, metal compounds such asmetal fluorides, oxides, sulfides, nitrides, carbides, phosphides,selenides, silicides and compounds thereof, as well as carbon,germanium, cermet, ferric oxide and the like. The absorber layers can beidentical, but can also be of different thickness and/or differentmaterial.

Materials to be used for the dielectric layer are primarily transparentmaterials with a low refractive index <1.7, for example SiO2, MgF, SiOxwith 1<x <2 and Al₂O₃. Almost all vapor-depositable, transparentcompounds can fundamentally be used, in particular also more highlyrefractive coating materials, such as ZrO₂, ZnS, TiO₂ and indium tinoxides (ITO). The layer thickness of dielectric layer D is in the rangeof 100 nanometers to 1000 nanometers, preferably 200 nanometers to 500nanometers.

Especially thin interference layers are preferred.

The absorber and dielectric layers of interference element I arepreferably produced by vacuum vapor deposition on substrate S, which canbe part of security element 1 but can also serve only as an intermediatecarrier and be removed at the latest when the security element isapplied to or embedded in an object.

A great variety of vapor deposition methods are suitable for producingthe layers. One systematic group is physical vapor deposition (PVD) withvapor deposition by boats, resistance heating, induction heating or alsoelectron beam, sputtering (DC or AC) and arc vapor deposition. On theother hand, vapor deposition can also be effected as chemical vapordeposition (CVD), e.g. sputtering in reactive plasma or any otherplasma-enhanced type of vapor deposition. It is fundamentally alsopossible to print dielectric layers on.

The structure of the interference element can be selected so that theinterplay of colors is the same or different depending on the viewingside of the security element. The interference element is preferably ofsymmetric design, i.e. the viewer perceives the same color shift effecton the front and back of the security element. Different effects resultfor example by varying the materials used in individual layers and/orvarying the layer thicknesses of the single layers building up theinterference element.

The interference element is of semitransparent design.“Semitransparency” refers in this connection to translucency, i.e. thelayer has a transparency of under 90 percent, preferably between 80percent and 20 percent.

Diffraction structures to be used are refraction patterns, transmission,volume or reflection holograms, as well as grid structures, which arepreferably part of the substrate bearing the interference element butcan also be incorporated into any other suitable layer or an additionallayer. The additional layer can be e.g. a lacquer layer.

The diffraction structures are preferably incorporated, in particularembossed, into the surface of a transparent plastic substrateconstituting the security element. The interference element can bepresent on the side of the plastic substrate where the relief structureis embossed, or on the opposite, smooth side of the substrate. Theinterference layers are then applied to the plastic substrate, inparticular vapor-deposited in a vacuum. Embossing of the plasticsubstrate can also be effected after the vapor deposition process,however. There are thus a plurality of variants that have differentvisual effects and can therefore be more or less preferable depending onthe purpose.

It is especially advantageous if the diffraction structures areconstituted by a relief pattern that directly adjoins the interferencelayer. Then the diffraction effects are almost equally well recognizablefrom each viewing side of the security element. If the security elementis embedded in a document as a two-sided windowed thread, thediffraction effect is visible from both sides. The same holds if thesecurity element is applied before a hole or as a lookthrough windowedthread when such a document is viewed in reflected light, for example ona base.

The optical effect of such a security element is determined essentiallyby the color effect of the interference element from both viewing sides.The diffraction structures essentially determine the optical appearanceat least from one viewing side, in the case of a suitable layerstructure from both viewing sides. In this case the effects of bothsecurity features overlap.

The diffraction effects stand out optically especially upon viewing inreflected light, e.g. if the document is resting on a base. Upon viewingin transmitted light, the diffraction effects distinctly recede. Thecolor shift effect is pronounced in both reflected light and transmittedlight.

Such a security element is particularly suitable for covering e.g.printed information on an object that is to be recognizable only at acertain viewing angle. With a security element that appears green at afirst viewing angle and golden at a second viewing angle, informationprinted for example in a golden color is recognizable only at the secondviewing angle. With a suitable color choice of the color shift effectand the information, the latter is thus well perceptible at certainviewing angles but almost invisible at other viewing angles.

Such a security element is especially suitable for use as a two-sidedsecurity thread since it shows from each viewing side especiallycharacteristic security features that are visually checkable. Such atwo-sided security thread can be used as an alternating security thread,that comes to the surface or is at least visible at different points ofthe security document on the opposite security document surfaces.However, it can also be used as a lookthrough windowed thread where itis visually recognizable from both sides of the document in anespecially thin or transparent area of the document or where it spans ahole in the document.

Such a security element is also suitable as a transfer element e.g. inthe form of a label or patch applied to one surface of the securitydocument over a hole. Viewed from one side of the document, there is theoptical impression of a patch with a color shift effect. Viewed from theother side, a section of the patch with a different or optionally anidentical color shift effect is seen through the hole of the document,it depending on the specific layer structure of the security elementwhether an optionally present diffraction design is recognizable fromboth sides or only from one side.

A “transfer element” according to the invention is a security elementthat is prepared on a separate carrier layer, for example a plasticfoil, in the reverse order to that in which it later comes to lie on thesecurity paper, and is then transferred to the security paper by meansof an adhesive or lacquer layer in the desired contour forms. The formof the security element is not limited, and any contour forms arepossible including filigree structures, such as guilloches, etc. Thesecurity elements are frequently also formed as strips extendingparallel to the edge of the document of value. The carrier layer can beremoved from the layer structure of the security element after transfer,or remains on the layer structure as a protective layer as a firm partof the security element.

The individual transfer elements can be prepared on the carrier layer asseparate individual elements in the contour forms to be transferred.Alternatively, the layer sequence of the transfer elements is providedon the carrier layer in continuous form. Such carrier layers withspaced-apart individual transfer elements or a continuously extendinglayer structure will be referred to hereinafter as “transfer material,”and the layer sequence of the security element disposed on the carrierlayer as the “transfer layer.”

In the case of the continuous transfer layer, the transfer material isthen connected with the security paper via an adhesive layer and theadhesive layer activated via suitable embossing tools so that thetransfer layer adheres to the security paper only in the activatedareas. All other areas are then removed with the carrier layer.Alternatively, the adhesive layer can also be executed in the form ofthe security element to be transferred. Hot-melt adhesives arepreferably used as adhesives. However, any other adhesives can also beused, such as reaction lacquers.

The inventively constructed security element can be combined withfurther security features, in particular with negative or positivewriting by locally removing at least one of the interference layers ofthe interference element. With a multilayer interference element, one upto all the layers can be locally removed. With an interference elementconsisting for example of a first absorber layer, a dielectric layeradjoining and overlying the first absorber layer and a second absorberlayer adjoining and overlying the dielectric layer, the gaps arepreferably located in the first and/or second absorber layer. Thewriting preferably consists of alphanumeric characters, but is notlimited thereto. It may involve any representable pattern, sign orencoding according to the invention. The gaps in the layer structurethus result in an additional reflected/transmitted light effect.

The signs, patterns and encodings of such a security element embedded ina document of value, for example as a security thread, are hardlyperceptible in reflected light but stand out distinctly when viewed intransmitted light as lighter areas compared to dark surroundings.Depending on which layers in the interference element are locallyremoved, color effects can also be controlled in reflected andtransmitted light.

BRIEF DESCRIPTION OF THE DRAWINGS

These properties and particular advantages of the individual variantswill be explained in the following with reference to the associateddrawings. The proportions shown in the figures do not necessarilycorrespond to the actual relations and serve primarily to improveclarity.

FIG. 1 shows a bank note with a semitransparent patch applied to onesurface over a hole in the bank note;

FIG. 2 shows a cross section through the bank note from FIG. 1 alongline II-II;

FIG. 3 shows a cross section through the bank note according to FIG. 1along line III-III with a lookthrough windowed thread;

FIG. 4 shows a cross section through the bank note according to FIG. 1along line IV-IV with a simple windowed security thread;

FIG. 5 shows the layer structure of a security element according to afirst embodiment;

FIG. 6 shows the layer structure of a security element according to asecond embodiment;

FIG. 7 shows the layer structure of a security element according to athird embodiment; and

FIG. 8 shows the layer structure of the security element according toFIG. 5 with gaps in the interference element.

The technical explanations on the individual figures will not berestricted to the particular embodiments shown, but also hold forexplaining the general inventive idea.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows security document 1, for example a paper bank note orplastic ID card, that is equipped with two security elements 2, 4. Firstsecurity element 2 is a patch that is applied to a surface of document 1as a label or transfer element over hole or other transparent area 3 ofdocument 1, for example by means of an adhesive. Second security element4 is a two-sided windowed security thread that is embedded in document 1either alternatingly or as a lookthrough windowed thread.

FIGS. 2 to 4 show the different manners of applying and embeddingsecurity elements 2 and 4 by way of example.

FIG. 2 shows security document 1 from FIG. 1 in cross section along lineII-II through the patch. Viewing such a bank note in reflected light,for example with it resting on a base, the diffraction effects stand outdistinctly. Viewed in transmitted light, the diffraction effects arehardly perceptible. Both in reflected light and in transmitted light thecolor shift effect at different viewing angles is retained.

The hole can be produced e.g. during papermaking by papermaking means orbe punched into the paper subsequently. With suitable design of thecolor shift effect and corresponding color coordination of print 5, theprint can be hidden under patch 2 at a certain viewing angle but bevisible at another angle. For example, a magenta print can be locatedunder a color shift element between magenta and green. At the viewingangle where the color shift element appears magenta, the print istherefore invisible and the color shift element seemingly opaque. At theviewing angle where the color shift element appears green, the printthereunder can be perceived and the color shift element appearssemitransparent. Patch 2 is recognizable from both sides in the area ofhole 3.

FIG. 3 shows the windowed security thread from FIG. 1 as a lookthroughwindowed thread. For this purpose, document 1, for example a bank note,has window areas 6 that are formed very thin and in extreme cases as ahole, so that security thread 4 is visible from both sides of document1. The optical effect of security thread 4 in reflected light andtransmitted light then corresponds to the appearance of patch 2described with respect to FIG. 2. Lookthrough window areas 6 have thesame function as hole 3. If the interference layers and diffractionstructures are selected so that the color shift effect is the sameregardless of the viewing side, true-to-side incorporation of thesecurity thread is also unnecessary.

The security thread can also be embedded in a document as an alternatingtwo-sided windowed security thread (not shown). The thread extends herein windows alternately visible on one and the other side of thedocument. Regardless of the viewing side of the document, the colorshift effect is then recognizable in the window areas.

Such a security thread 4 is of course also usable as a simple windowedsecurity thread that passes to the surface only on one side in windows7, as shown in FIG. 4.

Methods for embedding a two-sided alternating windowed thread forexample in bank notes are known to the expert.

FIGS. 5 to 8 show different layer structures of inventive securityelement 2, 4 in a detail view in cross section.

As explained in the following with reference to FIGS. 5 to 8, bothsecurity elements are of multilayer design and have an inventiveinterference element producing a color shift effect and overlaid withdiffraction structures. Accordingly, the interference element and thediffraction structures have an influence on the appearance of thesecurity element for each viewing side. Depending on the design of thelayer structure, the appearance of the security element can be the sameon both sides but also be different depending on the viewing side.

FIG. 5 shows a detail in cross section of the layer structure ofsecurity element 2. Security element 4 can be constructed accordingly.Transparent substrate S, preferably a plastic foil, has on one sideembossed holographic surface relief 8 that is overlaid directly byinterference element I. Alternatively, surface relief 8 can also beembossed in an additional lacquer layer, whereby the lacquer layer canbe present on one of the two substrate sides or on the external side ofabsorber layer A₁.

Interference element I, consisting of two absorber layers and onedielectric layer, has a dichroic color shift effect at different viewingangles, for example a change between green and magenta. If the samematerials and layer thicknesses are used for particular absorber layersA₁ and A₂ the security element has the same color shift effect on thefront and back. Any further interference layers and/or transparentlayers can be provided over interference element I.

The diffractive effect of a security element with a layer structureaccording to FIG. 5 is well recognizable from each viewing side inreflected light. In transmitted light, the diffractive effects recedealmost completely. The color shift effect is recognizable on both sidesof the security element both in reflected light and in transmittedlight.

Since the interference layers each have only a layer thickness of underone micron (the figures rendering the layer structure onlyschematically), all layers have the same relief pattern as reliefstructure 8 on which the layers are vapor-deposited. This has theconsequence that the holographic effects caused by relief structure 8are recognizable from both viewing sides. If the interference element isof symmetric design with a layer structure according to FIG. 5, such asecurity element can be used especially well as a two-sided securitythread because the diffractive effect and the color shift effect arealmost identical on both sides. When embedding the security thread onetherefore need not worry about trueness to side.

FIG. 6 shows an alternative layer structure of security element 2. Inthis case surface relief 8 is embossed in the substrate surface on theside of substrate S facing away from interference element I. Optionalprotective layer C covers sensitive relief structure 8. The refractiveindex of protective layer C differs essentially from the refractiveindex of substrate S so that the diffractive effect produced by therelief structure is as pronounced as possible. Alternatively, theprotective layer can also be a two-layer system. For example, a highlyrefractive layer, e.g. of TiO₂, ZnS, ZrO₂ or the like, can bevapor-deposited on relief structure 8 and a protective layer appliedthereto. In this case the refractive index of the protective layer neednot meet any special requirements.

When such a security document is viewed from absorber layer A₁, a colorshift effect is perceptible. Holographic effects do not occur on thisviewing side. When the same security element is viewed from the oppositeside, i.e. from the substrate side, a diffractive effect produced bydiffraction structure 8 and the color shift effect are perceptible.Altogether, a layer structure according to FIG. 6 thus produces ahologram effect combined with a color shift effect on one viewing side,and a color shift effect without overlaid diffractive effects on theother viewing side.

Instead of absorber layers A₁, A₂, dielectric layers D can also be used,whereby refractive index n of adjacent dielectric layers D must be verydifferent, on the one hand n<1.7 and on the other hand n>1.7, to cause adistinct color shift effect. Such a layer structure is shown in FIG. 7with four superimposed dielectric layers D_(1 to D) ₄. Apart from thedifferent layer structure of interference element I, security element 2according to FIG. 7 corresponds to security element 2 according to FIG.5. The color shift effect of such a layer structure is usually lesspronounced than with a structure as in FIG. 5. However, the lighttransmission is considerably higher, being >70 percent, often also >85percent.

FIG. 8 shows an advantageous embodiment of the invention whereininterference element I has gap 9, which is to be seen only in crosssection in FIG. 8. In a top view, gap 9 can have the form of signs,patterns or encodings. These patterns, signs or encodings opticallystand out particularly in transmitted light. The security element istransparent or at least semitransparent in the area of gaps 9 and showsno color shift effect or one differing from the areas surrounding thegaps. If the interference layers are removed completely in the gaps, thegaps can be made to appear completely colorless in transmitted light.This obtains an additional reflected/transmitted light effect. If such asecurity element is embedded for example in a bank note as a securitythread, gaps 9, which can have the form of signs, patterns or encodings,are less well or even hardly perceptible in reflected light, dependingon the design of the layer structure. When viewed in transmitted light,they stand out as light areas from the otherwise dark-looking securitythread. In reflected and transmitted light the color shift effect isvisible both from the substrate side and from the side opposite thesubstrate side. Additionally, the gaps are to be recognized intransmitted light. The diffractive effects due to diffraction structures8 are visible from both sides of the security element in reflectedlight. The color shift effects are no longer recognizable in the areasof the gaps.

Gaps 9 in interference element I can be produced by laser ablation on anintermediate carrier bearing interference element I, or only onsubstrate S. Substrate S can also be printed with soluble ink in thearea of gaps 9 before the interference layers are vapor-deposited, andin a following process the soluble ink can be dissolved with theinterference layers thereabove in the area of gaps 9. The expert isfamiliar with numerous other methods for producing gaps 9.

If the interference layers are not removed completely in the gaps, e.g.if gaps are only present in one or both absorber layers, the additionalpresence of diffraction structures can also be omitted.

EXAMPLE 1

In a surface of a transparent plastic foil, diffraction structures wereembossed. On these diffraction structures an interference element withthe following layer structure was vapor-deposited:

-   -   absorber layer of chromium with a layer thickness of 8        nanometers,    -   dielectric laser of SiO₂ with an optical path length of 480        nanometers,    -   absorber layer of chromium with a layer thickness of 8        nanometers.

The thus formed security element was applied to a bank note over a hole.The security element had a distinct color shift effect from green uponperpendicular viewing to magenta when viewed at an angle <45°.

When viewed in transmitted light the security element is translucent andthe color shift effect distinctly visible from both viewing sides. Thehologram effects receded almost completely when viewed in transmittedlight.

When viewed in reflected light on a base, however, the hologram effectis distinctly visible, from both sides of the security element. Thecolor shift effect is also distinctly visible. In combination with thecolored interference element the holographic effects aroused anextremely colorful impression in contrast to typical reflectionholograms with a metallic background.

EXAMPLE 2

The procedure is as in Example 1 except that the interference elementhas the following layer structure:

-   -   absorber layer of chromium with a layer thickness of 10        nanometers,    -   dielectric layer of SiO₂ with a layer thickness of 280        nanometers,    -   absorber layer of chromium with a layer thickness of 10        nanometers.

Generally and in all described embodiments, substrate S is preferablytransparent, possibly colored transparent or coated in coloredtransparent fashion. Substrate S is preferably a flexible plastic foilthat is cut into bands, threads or labels after embossing of reliefstructure 8 and after coating with interference element I. Substrate Scan also be present on a transfer foil and be transferred to thedocument by the transfer method, for example by hot stamping. Inaddition to the layer structures according to FIGS. 5 to 8, furtherprotective layers and in particular adhesive layers and cover layers cantherefore be provided so that the security element can either be gluedto an object as a label after removal of the cover layer or transferredas a transfer element by the transfer method.

1. A security document, or semifinished product for producing thesecurity document, comprising a substrate (1) with first and secondopposing substrate surfaces and a multilayer security element (2, 4)that is so connected with the substrate (1) that it is visuallyrecognizable at least from one of the two substrate surfaces, whereinthe security element includes a multilayer interference element (I)producing a color shift effect and a layer (S) with diffractionstructures (8) that at least partly overlaps the interference element(I), characterized in that the security element is semitransparent, theinterference element (I) has gaps in at least one layer, and thediffraction structures (8) directly adjoin the interference element (I).2. A security document or semifinished product according to claim 1,wherein the security element (2, 4) is applied to one of the twosubstrate surfaces and spans a hole (3) or a transparent area in thesubstrate (1).
 3. A security document or semifinished product accordingto claim 1, wherein the security element (4) is at least partly embeddedin the substrate (1) and spans a hole (3) or a transparent area in thesubstrate (1).
 4. A security document or semifinished product accordingto claim 3, wherein the security element (4) is so embedded in thesubstrate (1) that it is visually recognizable in first areas (7) of thesubstrate (1) on the first substrate surface and optionally additionallyin the second areas of the substrate different from the first areas onthe second substrate surface.
 5. A security document or semifinishedproduct according to claim 3, wherein the security element (4) is asecurity thread.
 6. A security document or semifinished productaccording to claim 1, wherein the interference element (I) is present ona transparent plastic substrate (S).
 7. A security document orsemifinished product according to claim 6, wherein the plastic substrate(S) is colored.
 8. A security document or semifinished product accordingto claim 1, wherein the interference element (I) includes a firstabsorber layer (A₁), a dielectric layer (D) adjoining and overlying thefirst absorber layer (A₁) and a second absorber layer (A₂) adjoining andoverlying the dielectric layer (D).
 9. A security document orsemifinished product according to claim 1, wherein the interferenceelement (I) includes at least three adjacent, mutually overlyingdielectric layers (D₁ to D₄) having alternately a high and a lowrefractive index.
 10. A security document or semifinished productaccording to claim 1, wherein the layers (A₁, D, A₂; D₁ to D₄)constituting the interference element (I) are vapor-deposited.
 11. Asecurity document or semifinished product according to claim 1, whereinthe interference element (I) has gaps (9) in the form of signs, patternsor encodings.
 12. A security document or semifinished product accordingto claim 6, wherein the plastic substrate (S) has the diffractionstructures (8).
 13. A security document or semifinished productaccording to claim 1, wherein the diffraction structures (8) are presentin a separate layer.
 14. A security document or semifinished productaccording to claim 1, wherein the diffraction structures (8) include anembossed relief pattern.
 15. A security document or semifinished productaccording to claim 1, wherein an effect caused by the diffractionstructures is visually recognizable from at least one of the sides ofthe security element depending on the way of viewing the securityelement.
 16. A security document or semifinished product according toclaim 1, wherein an effect caused by at least one of the diffractionstructures and a color shift effect produced by the interference elementis visually recognizable from both sides of the security elementdepending on the way of viewing the security element.
 17. A securitydocument or semifinished product according to claim 16, wherein theeffect caused by at least one of the diffraction structures and thecolor shift effect produced by the interference element are of identicaldesign from both sides of the security element depending on the way ofviewing the security element.
 18. A security element to be embedded inor applied to a security document (1), in particular for a paper ofvalue such as a bank note, wherein the security element includes amultilayer interference element (I) producing a color shift effect and alayer (S) with diffraction structures (8) that at least partly overlapsthe interference element (I), characterized in that the security elementis semitransparent, the interference element (I) has gaps in at leastone layer, and the diffraction structures (8) directly adjoin theinterference element (I).
 19. A security element according to claim 18,wherein the interference element (I) is present on a transparent plasticsubstrate (S).
 20. A security element according to claim 18, wherein theinterference element (I) includes a first absorber layer (A₁), adielectric layer (D) adjoining and overlying the first absorber layer(A₁) and a second absorber layer (A₁) adjoining and overlying thedielectric layer (D).
 21. A security element according to claim 18,wherein the interference layer (I) includes at least three adjacent,mutually overlying dielectric layers (D₁ to D₄) having alternately ahigh and a low refractive index.
 22. A security element according toclaim 19, wherein the layers (A₁, D, A₂; D₁ to D₄) constituting theinterference element (I) are vapor-deposited.
 23. A security elementaccording to claim 18, wherein the interference element (I) has gaps (9)in the form of signs, patterns or encodings.
 24. A security elementaccording to claim 19, wherein the plastic substrate (S) has thediffraction structures (8).
 25. A security element according to claim18, wherein the diffraction structures (8) are present in a separatelayer.
 26. A security element according to claim 18, wherein thediffraction structures (8) include an embossed relief pattern.
 27. Asecurity element according to claim 18, wherein an effect caused by atleast one of the diffraction structures and a color shift effectproduced by the overlying interference element are visually recognizablefrom both sides of the security element depending on the way of viewingthe security element.
 28. A security element according to claim 18 inthe form of a security thread to be embedded in a security document. 29.A security element according to claim 18 as a label or patch to beapplied to a security document.
 30. A security element according toclaim 18 as a transfer element to be applied to a security document by atransfer method.
 31. Transfer material for applying a security elementto a document of value, wherein the transfer material includes thefollowing layer structure: a multilayer interference element (I) with acolor shift effect, and a layer (3) with diffraction structures that atleast partly overlaps the interference element, characterized in thatthe security element is semitransparent, the interference element (I)has gaps in at least one layer, and the diffraction structures (8)directly adjoin the interference element (I).
 32. A method for producinga document of value having a security element, characterized in that thelayer structure of the transfer material according to claim 31 istransferred to the document of value in certain areas.
 33. Use of thesecurity document or semifinished product according to claim 1 forprotecting products.
 34. (canceled)
 35. (canceled)
 36. (canceled) 37.(canceled)
 38. (canceled)
 39. The security document or semifinishedproduct of claim 1, comprising paper of value.
 40. The security documentor semifinished product of claim 39 wherein said paper of value is abank note.
 41. The security document or semifinished product of claim11, wherein said gaps are present only in one of the layers of theinterference element.
 42. The security document or semifinished productof claim 41 wherein said gaps are in at least one of the absorberlayers.
 43. The security element of claim 23 wherein said gaps arepresent only in one of the layers of the interference element.
 44. Thesecurity element of claim 43 wherein said gaps are in at least one ofthe absorber layers.